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ADS1299EEGFE-PDK: Setup for testing of Evaluation board and Lead of current measurement.

sushant rajbhar
Prodigy 130 points
Part Number: ADS1299EEGFE-PDK
Other Parts Discussed in Thread: ADS1299

Hello Team TI,

Question 1:

We have received the Evaluation board for ADS1299. However we could not find any probe/ simulator to test the signal.

What testing accessories would be required to test the same?

Do I need to order some probes? If yes, what type of probes does TI suggest for evaluation?

If probes cannot be used, can TI suggest some other testing accessories? 

Question 2:

We are exploring active electrodes to use along with the ADS 1299 IC.

Having said that, I am aware that we won't be able to use the internal feature of current source for the lead off detection.

So, the plan is to use an external voltage source that will source the required current in nA.

Even though it is possible to use a current limiter resistor and measure the voltage drop across the resistor to find the current that is flowing to the body. I would like to measure the current in nA through an equipment.

The traditional multimeters are not capable of measuring such a low amount of current. Can TI suggest any equipment/ meter to measure the current?

  • 0
    TI__Mastermind 47595 points

    Hi Sushant,

    The device features an internal test signal in order to test the signal chain, however it is simply a square wave to verify operation of the signal chain. 

    A signal generator, or ECG simulator could be used to connect to the inputs as well. 

    I am not aware of a meter capable of measuring nA. It may very well exist, but it's probably quite expensive. 

  • 0 in reply to Alexander Smith
    Prodigy 130 points

    Hello Alex,

     Thankyou for your prompt reply.

    Let me reiterate the question.

    Say, I have developed a system using ADS IC which is measuring and displaying the brain waves.

    How do I evaluate that the received signal is correct and is not distorted because of the electrode wires, or any other factor..

    I intend the check the accuracy of the measured signal. Is there any equipment that TI had used while developing the system to validate the signals?

    I am aware that I can use a signal generator and check the accuracy. But how do I evaluate the actual EEG signals?

    As you said ECG simulator can be used, can you share the part number/ manufacturer of the ECG simulator ?

    Awaiting for your reply!

  • 0 in reply to sushant rajbhar
    TI__Mastermind 47595 points

    Hi Sushant,

    I am not aware of an instrument to help with this. The best answer I can suggest is to see what is received via the measurement and cross check the measured results vs the theoretically expected results. Evaluation of EEG signals is an emerging field and a very complicated subject. There is not a single way to evaluate them. 

    Fluke is an acceptable ECG simulator manufacturer, however there are many others that may suit your needs as well.  

  • 0 in reply to Alexander Smith
    Prodigy 130 points

    Hello Alexander,

     Can you please let me know how TI has validated the signals and confirmed it to be correct during testing the IC.

    Theoretically calculating the properties of EEG signals would be a very difficult I suppose.

    The concern here is still the same. Suppose I create an EEG measurement device using ADS1299. The cable length of the electrodes would be around 2meters in our case. How do I know that the signal that I am reading through my EEG system is the actual EEG signal and not any type of noise that can be incurred due to various reasons in the system. Since the EEG signal look much identical to noise in the time domain.

    Also, is there any proven design in the market using ADS1299 device?

    The solution of ECG simulator from Fluke is a good option but as the signal is in mV, the same can also be given through a signal generator.

  • 0 in reply to sushant rajbhar
    TI__Mastermind 47595 points

    Hi Sushant,

    I can't provide details about our test program on the public forum. But essentially, a very accurate input signal is applied and compared to the digitized output. Similar to what you can do with a signal generator. 

    It's inevitable that some noise gets into the measurement. Hence the need for analog and digital filtering. 

    Yes, there are several designs incorporating the ADS1299. 

  • 0 in reply to Alexander Smith
    Prodigy 130 points

    Hello Alex,

     I do not require the test program. I actually need to figure out a device/ equipment  which can be used without any doubt   as a substitute to the brain wave EEG signals.

    I and my team are looking for such EEG simulator but are unable to find one. We are also open to buy a signal generator which can provide the signal with amplitude of 1-2uV.

    We have the ADS1299 evaluation kit with us.

    The product which is to be designed needs to to comply all the medical standards and also the PMDA standards (Japanese standards)

    For the same reason, we need to be sure that the signal which would be read by the system is actually the brain wave and not any noise.

    We need a reference to check our product is working correctly or not. For the same reason, our requirement was to procure a equipment which can simulate the EEG signals which ultimately can be used for validation of the product.

    Also, I suppose apart from the open BCI platform, there are no open source designs available using ADS1299 IC.

    I cannot use open BCI to evaluate my product as open BCI does not holds any medical certification is not tested clinically.

    Hope you understand my concern.

    Regards,

    Sushant Rajbhar

  • 0 in reply to sushant rajbhar
    TI__Mastermind 47595 points

    Hi Sushant,

    We typically use the audio precision AP2700 (or similar models) for our precise signal generation needs.